The present invention relates to a new and improved construction of an electrical shock-proof fuse holder, especially a fuse holder for a fuse insert or fuselink possessing two electrically conductive end caps mechanically connected with one another by an insulating body and electrically by a fuse wire or the like.
Generally speaking, the fuse holder of the present development is of the type comprising a housing formed of electrically insulating material comprising a receiving tube or tube member extending along a predetermined lengthwise axis. The receiving tube possesses a wall provided with an opening or recess disposed substantially parallel to the predetermined lengthwise axis. A cradle-like carrier or carrier member is removably inserted into the receiving tube and is also formed of electrically insulating material. The cradle-like carrier is locked in its work position when inserted into the receiving tube and closes the receiving tube when located in such work position. The cradle-like carrier or carrier member includes a cradle or vat extending in the direction of the predetermined lengthwise axis and formed to receive the fuse insert or fuselink which is also disposed so as to extend essentially in the direction of the predetermined lengthwise axis. To release or unlock the cradle-like carrier, the latter is turned or rotated about the predetermined lengthwise axis and, without further rotational movement or rotary motion, it is pulled out or displaced with respect to the receiving tube in the direction of the predetermined lengthwise axis such that the cradle-like carrier is in a rest position to allow replacement of the fuse insert or fuselink. Two contact pieces or contacts are each electrically conductively connected with an exterior connecting part. These two contact pieces are mounted to be electrically insulated from each other at the housing. These contact pieces extend radially resiliently and inwardly from the same side through the opening or recess into the receiving tube, thus each making electrically conducive contact with an associated end cap of the fuse insert or fuselink located in ; the cradle-like carrier which is locked in its work position. The cradle-like carrier in its released position as well as during the pulling out thereof electrically insulates the two end caps relative to the contact pieces.
A fuse holder of the aforementioned type is known, for example, from the U.S. Pat. No. 4,329,006, granted May 11, 1982. Compared with conventional fuse holders which have a contact at the base of the receiving tube engaged axially by one end cap of the fuse insert and a lateral contact which can be only indirectly contacted by the other end cap of the fuse insert via a connecting conductor of the carrier, the fuse holder described in this U.S. Pat. No. 4,329,006, has the advantage that it possesses a short overall length and a small number of components which allow for simple assembly. Electrical shock-proof safety during the course of replacing the fuse insert is ensured because the released fuse carrier insulates both end caps of the fuse insert with respect to both contact pieces located on the same side of the receiving tube while the fuse carrier is being removed from or inserted into the holder. In order to grasp the head member of the fuse carrier, it must be left in a position such that it is slightly protruding because, in contrast to fuse holders with an axial base contact, the head member does not emerge or protrude during unlocking. When the head member of the fuse carrier is fully inserted, it must be pryed out with great effort and this work cannot not be accomplished without a certain amount of danger. It is to be appreciated that when the contacts located in the receiving tube cannot be contacted from the front with the standardized test finger in accordance with the IEC (International Electrotechnical Commission) 529 Standard, also then when the fuse carrier is removed, then the fuse holder is considered to be electrically shock-proof. However, this prior art construction of the head member which can be readily manually extracted does not provide adequate protection for children. A child playing with, for instance, a thin conductive object such as a knitting-needle or the like, can poke into the fuse holder and this can cause an accident.